Pneumatic compressor



(No Model.) 2 Sheets-Sheet 1.

J. B. ROOT.

PNEUMATIC COMPRESSOR.

No. 283,925. Patented Aug. 28, 1883.

(No- Model.) 2 SheetsShee't 2.

PNEUMATIC COMPRESSOR. No. 283,925. Patented Aug. 28,1883.

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I k 0 J z Gaga/M Em En STATES PATENT FFICE.

PNEUMATIC COMPRESSOR.

SPECIFICATION forming part of Letters Patent No. 283,925, dated August 28, 1883.

Application filed December 11, 1882. (No model.)

To all w/wm it may concern/.-

Be it known that I, J OHN B. RooT, of Port Chester, in thecounty of WVestchester and State of New York, have invented certain new and useful Improvements in Pneumatic Compressors; and I hereby declare the following to be a clear, concise, and exact description of the same, when read in connection ,with the accompanying drawings.

My invention relates to that class of pneumatic compressors in which freely-moving or detached pistons are used-that is, pistons which have no connection with other devices for transmitting the force imparted to them.

It consists of an upright cylinder having an actuating-chamber at its lower end, anda com pressingchamber at its upper end, and a detached piston separating such chambers, the actuating-chamber being provided with valves for the induction and eduction of steam or other fluid for operating the piston, and the compressing-chamber being provided with a passage or passages for the induction and eduction of air or other fluid to be operated upon, such valves an d passages being so arranged that a cushion of steam is formed at the lower end and a cushion of air at the upper end of the cylinder, to check the piston at each end of its stroke; and it consists, further, in means for working the steam expansively, and in amovable packing-ring for admitting steam under the plunger when the steam-port is closed by the piston.

In the iollowing description I explain my invention as embodied in a machine for compressing air, such machine being driven by steam; but the same mechanism may be used to compress and be operated by other fluids or gases.

1n the drawings, Figure 1 is a central vertical section of the compressor. Fig. 2 is a side view of the same, partially sectioned on the line 1 3 of Fig. 1; and Fig. 3 is a plan View of the machine as shown in Fig. 2. The ports are seen in the position in which the air end of the cylinder has inducted nearly its full supply of air, and the plunger, by its down- 'ward movement, has opened the valve which admits steam into the steam-chamber.

A is a suitable pedestal or base, which supports the other parts of the machine, and B is an. upright cylinder containing the piston or plunger D, which is free from any attachments or connections, and is arranged to separate and reciprocate between the air-chamber E and the steam-chamber F. This cylinder is bolted directly to the base A, suitable packing being interposed between the parts to form a steam-tight joint. The upper end of this cylinder is closed by a cover, 0, bolted to a flange, G, suitable packing beingalso interposed be tween these parts to secure an airtight joint.

Surrounding the upper end of the cylinder is an annular hood, H, which is divided by partition-walls it into two chambers, which communicate, respectively, with the in du cti onvalves I and with the eductionwalves I, and are provided with an inlet, H, for admitting the air, and an outlet, IP, for conveying the com-pressed air to areceiver, or to the devices in which it is used.

In the side of the piston D is a cam-groove, J, into which penetrates the tongue K of the valve K, which valve is arranged to have a rocking motion upon the shaft k, and is in closed in the steam-chest K. Steam is admitted to and exhausted from the steam-chamber F through the port M, which is connected by a passage in the walls of the cylinder (shown in dotted lines) with the port M of the steamchest, so that when the valve K is in the position shown the port M communicates with the steam-supply pipe L; but when the port M is covered by the rocking valve the steam in the cylinder B is in a condition to expand, and when the valve has moved to a position beyond the port M the steam in the cylinder is free to exhaust through the port M into the space in which the valve-tongue K vibrates, and out at the port M (shown in central section inthe first figure and located between the steam-chest and the wall of the cylinder) into the waste-pipe m.

The piston or plunger D is provided with which is loose in its groove. This is for the purpose of allowing steam to leak past this ring from the port M through ports (I into the steanrchamber and raise the piston, so that it may take full steam. This insures the entering ure of the steam become so reduced that the elasticity of the stea1n-cushion formed in the bottom of this chamber would not suffice to two packing-rings, D D, the lower one of of the steam to the chamber F should the pressadvance the piston beyond the port M, and when, for any other reason, the piston has come to rest in such aposition that it closes the port M. The upper packing-ring is fast in its groove and prevents any steam which may pass the lower ring from penetrating farther between the parts. Ordinarily, however, the steam-cushion is sufficiently elastic to lift the piston above the port M, and a pressure is maintained upon the lower ring, which keeps it tightly in place and causes it to make asufficiently close bearing.

Instead of depending upon the ports (1 to admit steam beneath the piston when the port M is covered, particularly in starting the machine, a pipe, 0, is used, which conveys steam directly from the steam-chest to the steamchamber. A cock, 0, shuts off the steam when the machine is in motion.

The steam-chamber is drained of any water that may accumulate by a petcock, 1?, and the steam-cushion formed therein is extended and contracted by connecting and disconnecting the steam-bulbs Q Q, which open into each other and into this chamber, by cock Q, thereby regulating the clearance of the piston at the end of its downstroke. The valves of the air-chamber are'located at a short distance from the upper end of the cylinder, and thereby permit the formation of an air-cushion at the end of the upstroke of the piston, which cushion checks the upward movement of the and allows steam to slowly work around it and through the ports which lead from its seat to the steam space. This will cause the piston to rise until it has uncovered the steam-port in the wall of the cylinder, when it takes full. steam and shoots upward with great force, comprcssingthe air in the airchamber and expelling it through the air-eduction passages or valves. During this upward stroke the tongue of the steam-valve engages, first, with the cam J of the cam-groove J to close the induction-port M, and as the expansion of the steam and the momentum acquired keep the plunger in motion, this tongue engages next with the cam J 2 and moves the valve so that the port M is connected with the exhaust-port M and the steam in the cylinder is allowed to exhaust; and this exhaust commences considerably before or-at the time when the plunger, having cushioned on the air in the space'above the air-valves, begins its return or down stroke under the combined influence of gravity and the recoil of the air-cushion. As the lower end of the piston passes the port M the tongue of the steam- 1 valve is caught on lip J of the cam-groove and the valve is rocked to the position shown in the drawings, thereby supplying the port M with live steam, so that as the piston rebounds from the steam-cushion under the influence of the energy acquired by such cushion in arresting its downward movement, and which is now .converted into upward movement, it may, in addition to the momentum derived from the steam-cushion, again receive full head of steam and repeat the movements just described.

It is essential that the piston be sufficiently heavy to absorb the force imparted to it at the commencement of its upstroke and ac quire the necessary momentum to overcome the elasticity of the air, and by compressing it transfer thereto its stored-up power.

The features of my invention are not conthey might be arranged to operate by power derived from one or both of the elastic cushions, or by other means independent of direct connection with the plunger. Then, too, the air-chamber may be changed according to the work to be done, and may be separated from the steamchamber, so as to have no other connection therewith than the piston common to both; and, further, a piston-rod might be con nected to the plunger and give motion to a piston-head in a secondary cylinder for the purpose of compressing or pumping other fluids.

\Vhat I claim as new is 1. The combination, in a pneumatic compressor, of an upright cylinder having an actuating-chamber at its lower end, which is pro- .vided with suitable valves for the induction and eduction of an expansible actuating-fluid, and a compressing-chamber at its upper end,

which is provided with a passage or passages for the induction and eduction of the fluid acted upon, and a detached piston arranged to reciprocate between said chambers, said valves and passages being arranged to permit the forming of a cushion at each end of the stroke of the piston, substantially as described, and for the purpose set forth.

2. In a pneumatic compressor provided with an actuating-chamber, the combination of a freely reciprocating or detached piston with valve-gear or other means for closing the induction-port of the actuating-chamber before the piston reaches the limit of its stroke, for the purpose of working the actuating-fluid expansively, substantially as described.

3. In an air-compressor, a detached piston provided with packing-rings D D, one being loosed and arranged to act as a valve and the other being fixed, as and for the purpose set I 

